Reduction of the Clavicles in the Mesoenatidae, with Some Remarks Concerning the Relationship of the Clavicle to Flight-Function in Birds

Author Institution: Blue Sea Lake Biological Laboratory, Messines, Quebec, and Division of Birds, U. S. National Museum, Washington, D. C

Cosmological Relativity: A General-Relativistic Theory for the Accelerating Expanding Universe

Recent observations of distant supernovae imply, in defiance of expectations, that the universe growth is accelerating, contrary to what has always been assumed that the expansion is slowing down due to gravity. In this paper a general-relativistic cosmological theory that gives a direct relationship between distances and redshifts in an expanding universe is presented. The theory is actually a generalization of Hubble's law taking gravity into account by means of Einstein's theory of general relativity. The theory predicts that the universe can have three phases of expansion, decelerating, constant and accelerating, but it is shown that at present the first two cases are excluded, although in the past it had experienced them. Our theory shows that the universe now is definitely in the stage of accelerating expansion, confirming the recent experimental results

Classification of multifluid CP world models

Various classification schemes exist for homogeneous and isotropic (CP) world models, which include pressureless matter (so-called dust) and Einstein's cosmological constant Lambda. We here classify the solutions of more general world models consisting of up to four non-interacting fluids, each with pressure P, energy density epsilon and an equation of state P = (gamma - 1) epsilon with 0 <= gamma <= 2. In addition to repulsive fluids with negative pressure and positive energy density, which generalize the classical repulsive (positive) Lambda component, we consider fluids with negative energy density as well. The latter generalize a negative Lambda component. This renders possible new types of models that do not occur among the classical classifications of world models. Singularity-free periodic solutions as well as further `hill-type', `hollow-type' and `shifting-type' models are feasible. However, if one only allows for three components (dust, radiation and one repulsive component) in a spatially flat universe the repulsive classical Lambda fluid (with Lambda > 0) tends to yield the smoothest fits of the Supernova Ia data from Perlmutter et al. (1999). Adopting the SN Ia constraints, exotic negative energy density components can be fittingly included only if the universe consists of four or more fluids.Comment: 12 pages, 11 figures, latex, A&A in pres

Agroecology and Food Sovereignty

We propose that agroecology provides a framework for understanding ‘levels’ for the transition to sustainable food systems. If we agree that agroecology includes social and political dimensions of governing territorial food systems, then it must be linked to movements for food sovereignty. However, the concentration of power in food and farming systems locks in industrial logic, posing immense barriers to agroecological and social transition. This creates a tension between efforts at convergence of food system innovations from below, versus co-optation of grass-roots language and practices by private and public actors who are committed not to changing the logic of industrial agriculture, but instead to reducing its harm. We suggest agroecological and food sovereignty movements consciously embrace this tension as a dance of creativity and appropriation. If this dance can be made generative rather than deadly, it can open pathways for transition to new ways of seeing, experiencing, and getting food.International Panel of Experts on Sustainable Food Systems (iPES Food

Aeroelastic simulation of higher harmonic control

This report describes the development of an aeroelastic analysis of a helicopter rotor and its application to the simulation of helicopter vibration reduction through higher harmonic control (HHC). An improved finite-state, time-domain model of unsteady aerodynamics is developed to capture high frequency aerodynamic effects. An improved trim procedure is implemented which accounts for flap, lead-lag, and torsional deformations of the blade. The effect of unsteady aerodynamics is studied and it is found that its impact on blade aeroelastic stability and low frequency response is small, but it has a significant influence on rotor hub vibrations. Several different HHC algorithms are implemented on a hingeless rotor and their effectiveness in reducing hub vibratory shears is compared. All the controllers are found to be quite effective, but very differing HHC inputs are required depending on the aerodynamic model used. Effects of HHC on rotor stability and power requirements are found to be quite small. Simulations of roughly equivalent articulated and hingeless rotors are carried out, and it is found that hingeless rotors can require considerably larger HHC inputs to reduce vibratory shears. This implies that the practical implementation of HHC on hingeless rotors might be considerably more difficult than on articulated rotors

Radon and lung cancer: case-control studies versus ecologic studies

Problems in epidemiological studies in connection with the determination of radon-caused lung cancer are discussed. Biasing and confounding effects have led to very divergent results in epidemiological studies and there is still doubt on the carcinogenic effect of radon progenies in the concentration range of usual indoor air (say below several hundred Bq/m3). Nevertheless, epidemiological investigations seem to be the key tool to decide this question. Main advantages and disadvantages of case-control and ecologic studies are discussed and an overall uncertainty estimation is given for both types of investigations

Report of Virtual Conference. BASICS Phase I - Achievements and Learnings Meeting. May 18-19, 2020

The Building an Economically Sustainable Integrated Cassava Seed System in Nigeria (BASICS) project began in 2016 and formally ends on 30 June 2020. The project has made progress in demonstrating that commercially viable production and sale of breeder, foundation and certified seed is possible. Furthermore, the project has established a strong basis for building a sustainable seed system by developing building blocks across the seed value chain. This meeting had the following objectives: 1. To identify the achievements and lessons learned in each of the project components; 2. To identify the shortcomings in each component (what would I do differently, knowing what I know now?), remaining challenges and ideas to overcome them; 3. To assess and discuss the challenges and progress made in integrating the components into an integrated seed system and identify ways integration can be improved; 4. To assess and discuss the commercial sustainability of the seed system and identify options to promote its sustainability and further scaling; and 5. To make plans for the publication of the findings and lessons learned during BASICS-

Entropic Accelerating Universe

To accommodate the observed accelerated expansion of the universe, one popular idea is to invoke a driving term in the Friedmann-Lemaitre equation of dark energy which must then comprise 70% of the present cosmological energy density. We propose an alternative interpretation which takes into account the entropy and temperature intrinsic to the horizon of the universe due to the information holographically stored there. Dark energy is thereby obviated and the acceleration is due to an entropic force naturally arising from the information storage on the horizon surface screen. We consider an additional quantitative approach inspired by surface terms in general relativity and show that this leads to the entropic accelerating universe.Comment: 14 pages, 1 figure, extended and clarifie

1980 Ruby Yearbook

A digitized copy of the 1980 Ruby, the Ursinus College yearbook.https://digitalcommons.ursinus.edu/ruby/1083/thumbnail.jp

Symmetric Strategy Improvement

Symmetry is inherent in the definition of most of the two-player zero-sum games, including parity, mean-payoff, and discounted-payoff games. It is therefore quite surprising that no symmetric analysis techniques for these games exist. We develop a novel symmetric strategy improvement algorithm where, in each iteration, the strategies of both players are improved simultaneously. We show that symmetric strategy improvement defies Friedmann's traps, which shook the belief in the potential of classic strategy improvement to be polynomial